Monetary instruments issued by governments such as money or currency are used throughout the world today. Government-issued currency typically includes banknotes (also known as paper currency or bills) having visible markings printed on high-quality paper, plastic, or paper impregnated with other materials, such as plastic. The visible markings indicate the denomination (value) of the banknote, includes a serial number, and has decorations such as images, and anti-counterfeiting structures such as special threads, ribbons, and holograms. Currency circulates within an economic system as a medium of monetary exchange having a fixed value until it is physically worn out. Worn out banknotes are generally returned by banks or other financial institutions and then replaced.
Other privately issued monetary instruments are also used, such as credit cards and gift cards. These cards typically include an electronically accessible value (e.g., stored in a magnetic stripe or in a chip in the card) or an electronically accessible account that can be used to make purchases. However, the value of the card is not readily viewed by a user without special equipment, such as a reader.
In the past, banknotes have not been electronically enabled. However, more recently there have been proposals to use RFID (radio-frequency identification device) in banknotes to validate the banknote and avoid counterfeiting. For example, U.S. Pat. No. 8,391,688 and U.S. Pat. No. 8,791,822 disclose systems for currency validation. U.S. Pat. No. 5,394,969 describes a capacitance-based verification device for a security thread embedded within currency paper to defeat counterfeiting. Security systems for scanning a paper banknote and checking identification information in the banknote (e.g., the serial number) with a network-accessible database have been proposed, for example in U.S. Pat. No. 6,131,718. In all of these systems, however, there is no way to visibly test small details of a banknote without using a separate electronic or optical reader.
There remains a need therefore, for currency providing a variable value that is electronically accessible with visible indicia without using a separate electronic or optical reader.